Split-bus electrical panel in parallel configuration to maximize pv/battery inverter back-feed power

ABSTRACT

An apparatus provides a single split-bus electrical panel with back-feed circuit breakers arranged and sized so that, for example, a single 225A rated split-bus electrical panel with a 200A main breaker may be used to connect a far higher photovoltaic power source than conventional configurations. The circuit breakers are connected to a Microgrid Interconnection Device for isolation of critical loads during a utility power outage. A first panel section of the split-bus panel is connected to a utility and supplies power to non-critical loads. A second panel section is connected to a renewable power source with battery back-up to supply power to the critical loads and is connected through a relay to the utility, in parallel with the first panel section, to supply both utility power and renewable power when there is no outage. The relay is configured to isolate the second panel when there is a utility outage.

TECHNICAL FIELD

The present disclosure relates to residential electrical panels formaximizing power of a photovoltaic system with battery back-up to powercritical household loads during a utility power outage.

BACKGROUND

When an electrical utility outage occurs, critical loads such as pumps,security systems, refrigerators and electronics should ideally have anauxiliary source of power available. In residential applications,photovoltaic (PV) systems with battery back-up are available to providelimited auxiliary power, which is typically at a lower power level thanis available from the utility. Thus, some means is required to allocatethe reduced power to the critical loads. The installation of typicalresidential PV systems requires a separate back-up panel for thecritical loads, so that the critical loads must be relocated to theseparate back-up panel.

When adding an alternate energy source to an electrical system of ahome, the National Electrical Code allows an extra 20% of electricalpower to be added to a panel beyond its rating, provided the breakerfeeding in this alternate energy is at the opposite end of the bus barto the main breaker. A conventional 200 A rated panel, protected by a200 A main breaker, may have up to 40 A of photovoltaic power added.Meanwhile a 225 A rated panel with a 200 A main breaker is allowed aphotovoltaic back-feed of 70 A . For a pure photovoltaic installationthis is often sufficient, but when a battery-based back-up system isadded, this is sometimes not enough.

What is needed is a simplified, residential electrical panel forintegration of a photovoltaic system with battery back-up to powercritical household loads during a utility power outage, which enablesconnection to a far higher photovoltaic power source than allowed withconventional configurations.

SUMMARY

In accordance with one example embodiment described herein, an apparatusprovides a single split-bus electrical panel with back-feed circuitbreakers arranged and sized so that, for example, a single 225 A ratedsplit-bus electrical panel with a 200 A main breaker may be used toconnect a far higher photovoltaic power source than allowed withconventional configurations. Two sections of the single split buselectrical panel are connected in parallel, allowing much morephotovoltaic power to be connected. For example, two 225 A panelsections of the split-bus panel each have a 110 A rated feed breaker.The panel section's rating may be increased by 120% of the 225 A to 270A . The difference of the 270 A rating for the panel section from the110 A rating for the breaker, allows a maximum rating of 160 A forphotovoltaic power that may be connected to the panel section.

The back-feed circuit breakers are arranged to allow connection of aMicrogrid Interconnection Device (MID) for isolation of a critical loadssection from a standards loads section during back-up operation due to autility power outage. The first panel section of the split-buselectrical panel is connected to a utility power source and suppliespower to non-critical standards loads. The second panel section of thesplit-bus electrical panel is connected to a renewable power source withbattery back-up to supply power to critical loads in a residence whenthere is a power outage. The second panel section is connected through arelay to the utility power source, in parallel with the first panelsection, to supply both utility power and renewable power when there isno outage. The relay is configured to isolate the second panel whenthere is a utility power outage.

In accordance with one example embodiment described herein, apparatusfor maximizing power of a photovoltaic system to power criticalresidential loads during a utility power outage, comprises:

a single, split-bus electrical panel including a first panel section ofthe split-bus electrical panel configured to supply power tonon-critical standard electrical loads and a second panel section of thesplit-bus electrical panel configured to supply power to criticalelectrical loads by a back-up system, the critical loads required to bepowered during a utility power outage;

a first circuit breaker in the first panel section connected to a firstbus bar and a second bus bar of the first panel section, the firstcircuit breaker configured to conduct utility power from a utility powersource;

a second circuit breaker in the second panel section connected to afirst bus bar and a second bus bar of the second panel section, thesecond circuit breaker connected through a relay to the utility powersource in parallel with the first circuit breaker, the second circuitbreaker configured to conduct the utility power from the relay to thefirst bus bar and the second bus bar of the second panel section whenthere is no utility power outage, and to be isolated by the relay fromthe utility power source when there is a utility power outage;

a third circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a renewable energy power source of the back-up system,configured to conduct renewable energy power to the first bus bar andthe second bus bar of the second panel section; and

a fourth circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a back-up power source of the back-up system, configured toconduct back-up power to the first bus bar and the second bus bar of thesecond panel section to supplement the renewable energy power at leastwhen a utility power outage is detected by the back-up power source.

In accordance with one example embodiment, the relay is configured to beclosed and conduct utility power from the utility power source to thesecond circuit breaker when there is no utility power outage and to beopen when there is a utility power outage.

In accordance with one example embodiment, an outage detector isassociated with the back-up power source and is configured to detectwhether there is a utility power outage and to send an outage signal tothe relay to open when a utility power outage is detected.

In accordance with one example embodiment, the renewable energy powersource of the back-up system is at least one of a photovoltaic solararray or a wind energy array.

In accordance with one example embodiment, the first, second, third, andfourth circuit breakers are two-pole circuit breakers operating asback-feed circuit breakers.

In accordance with one example embodiment, the utility power is 120/240VAC Split Phase Electrical power.

In accordance with one example embodiment, the relay is a component of amicrogrid interconnection device.

In accordance with one example embodiment, the first panel is connectedthrough the relay in parallel with the second panel when there is noutility power outage.

In accordance with one example embodiment, the back-up power source ofthe back-up system includes a rechargeable battery, a charger, aninverter, and an outage detector that is configured to detect when thereis a utility power outage and send an outage signal to the relay.

In accordance with one example embodiment, the back-up power source ofthe back-up system includes a rechargeable battery and a charger thatreceives the utility power from the fourth circuit breaker to charge therechargeable battery when there is no utility power outage.

In accordance with one example embodiment, the first panel section andthe second panel section are connected in parallel, and each panelsection is fed and protected by its own feed breaker whose currentrating is significantly below the bus rating of the panel section. Thislarge difference between bus rating and feed breaker rating is whatallows a large amount of solar capacity to be backfed to the panelsection.

In accordance with one example embodiment, an outage detector isassociated with a microgrid connection device and is configured todetect whether there is a utility power outage and to cause the relay toopen when a utility power outage is detected.

In accordance with one example embodiment described herein, an apparatusfor maximizing power of a photovoltaic system to power criticalresidential loads during a utility power outage, comprising:

a single, split-bus electrical panel including a first panel section ofthe split-bus electrical panel configured to supply power tonon-critical standard electrical loads and a second panel section of thesplit-bus electrical panel configured to supply power to criticalelectrical loads by a back-up system, the critical loads required to bepowered during a utility power outage;

a first circuit breaker in the first panel section connected to a firstbus bar and a second bus bar of the first panel section, the firstcircuit breaker configured to conduct utility power from a utility powersource;

a second circuit breaker in the second panel section connected to afirst bus bar and a second bus bar of the second panel section, thesecond circuit breaker connected through a relay to the utility powersource in parallel with the first circuit breaker, the second circuitbreaker configured to conduct the utility power from the relay to thefirst bus bar and the second bus bar of the second panel section whenthere is no utility power outage, and to be isolated by the relay fromthe utility power source when there is a utility power outage;

a third circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a renewable energy power source and a back-up power sourceof the back-up system, configured to conduct renewable energy power andback-up power to the first bus bar and the second bus bar of the secondpanel section, the back-up power to supplement the renewable energypower at least when a utility power outage is detected.

In accordance with one example embodiment, the first panel section andthe second panel section are connected in parallel, and each panelsection is fed and protected by its own feed breaker whose currentrating is significantly below the bus rating of the panel section. Thislarge difference between bus rating and feed breaker rating is whatallows a large amount of solar capacity to be backfed to the panelsection.

In accordance with one example embodiment, a system for maximizing powerof a photovoltaic system to power critical residential loads during autility power outage, comprises:

a single, split-bus electrical panel including a first panel section ofthe split-bus electrical panel configured to supply power tonon-critical standard electrical loads and a second panel section of thesplit-bus electrical panel configured to supply power to criticalelectrical loads by a back-up system, the critical loads required to bepowered during a utility power outage;

a first circuit breaker in the first panel section connected to a firstbus bar and a second bus bar of the first panel section, the firstcircuit breaker configured to conduct utility power from a utility powersource;

a relay connected to the utility power source, configured to be closedand conduct utility power from the utility power source when there is noutility power outage and to be open when there is a utility poweroutage;

a second circuit breaker in the second panel section connected to afirst bus bar and a second bus bar of the second panel section, thesecond circuit breaker connected through the relay to the utility powersource in parallel with the first circuit breaker, the second circuitbreaker configured to conduct the utility power from the relay to thefirst bus bar and the second bus bar of the second panel section whenthere is no utility power outage, and to be isolated by the relay fromthe utility power source when there is a utility power outage;

a third circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a renewable energy power source of the back-up system,configured to conduct renewable energy power to the first bus bar andthe second bus bar of the second panel section;

a fourth circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a back-up power source of the back-up system, configured toconduct back-up power to the first bus bar and the second bus bar of thesecond panel section to supplement the renewable energy power at leastwhen a utility power outage is detected by the back-up power source; and

an outage detector associated with the back-up power source, configuredto detect whether there is a utility power outage and to send an outagesignal to the relay to open when a utility power outage is detected.

The resulting apparatus and system connect the two panel sections of thesplit bus in parallel, allowing much more photovoltaic power to beconnected. For example, two 225 Ampere panel sections of the split-buspanel each have a 110 Ampere rated breaker. The panel section's ratingmay be increased by 120% of the 225 Amperes to 270 Amperes. Thedifference of the 270 Ampere rating for the panel section from the 110Ampere rating for the breaker, allows a maximum rating of 160 Amperesfor photovoltaic power that may be connected to the panel section.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed description of the disclosure, briefly summarized above,may be had by reference to various embodiments, some of which areillustrated in the appended drawings. While the appended drawingsillustrate select embodiments of this disclosure, these drawings are notto be considered limiting of its scope, for the disclosure may admit toother equally effective embodiments.

FIG. 1 is circuit and functional block diagram of a single split-buselectrical panel with back-feed circuit breakers arranged to allowconnection of a Microgrid Interconnection Device (MID) for isolation ofa critical loads section from a standards loads section during back-upoperation due to a utility power outage, according to an exampleembodiment of the disclosure.

FIG. 2 is circuit and functional block diagram of an alternate exampleembodiment of the single split-bus electrical panel of FIG. 1, whereinthe back-up battery provides back-up direct current to the solarinverter, which is combined with the photoelectric direct current fromthe photovoltaic solar array, the combined currents being converted bythe solar inverter to alternating current that is provided to the thirdcircuit breaker, according to another example embodiment of thedisclosure.

Identical reference numerals have been used, where possible, todesignate identical elements that are common to the figures. However,elements disclosed in one embodiment may be beneficially utilized onother embodiments without specific recitation.

DETAILED DESCRIPTION

FIG. 1 illustrates an example of a single split-bus electrical panel 100with back-feed circuit breakers 110A and 110B arranged to allowconnection of a microgrid interconnection device (MID) 116 for isolationof a critical loads section 108B from a standard loads section 108Aduring a back-up operation due to a utility power outage. The singlesplit-bus electrical panel apparatus 100 isolates critical electricalloads during a utility power outage, such as freezers, security systems,or electronic medical devices, to enable them to be powered by arenewable energy power source of a back-up system. The back-up systemmay be powered, for example, by at least one of a photovoltaic solararray 132 or a wind energy array. A first or lower panel section 102A ofthe split-bus electrical panel 100 supplies power to the non-criticalstandard loads 108A, such as general lighting, in a residence. A secondor upper panel section 102B of the split-bus electrical panel 100supplies power to the critical loads 108B in the residence, which mustcontinue to be powered during a utility power outage.

In accordance with an example embodiment, a main incoming circuitbreaker 103 is connected to an electric power utility that provides120/240 VAC split phase electrical power for distribution by thesplit-bus electrical panel 100 to branch circuits of the residence. Theutility supplies two 120 VAC phases L1 and L2 that are 180° out of phasewith each other (split phases), and a grounded neutral voltage N. Themain incoming circuit breaker 103 may be connected to the L1 leg and theL2 leg of the split-phase electrical power, and the grounded neutralvoltage N may be connected to a neutral terminal of the split-buselectrical panel 100. The main incoming circuit breaker 103 may have anexample rating of 200 Amperes.

The first 120 VAC phase L1 is between the L1 leg and the groundedneutral N, the phase L1 and is connected from the main breaker 103 vialine 107 to a terminal 4 of a terminal block 142 of the split-buselectrical panel 100. The second 120 VAC phase L2 is between the L2 legand the grounded Neutral N, the phase L2 and is connected from the mainbreaker 103 via line 105 to a terminal 1 of the terminal block 142. A240 VAC service may be available between the Leg L1 and the Leg L2 ofthe split-phase electrical power.

A first two-pole circuit breaker 110A in the first panel section 102Amay be oriented as a back feed breaker to connect the L1 bus bar 104A toterminal 4 of the terminal block 142 via line 111 and to phase L1 fromthe main circuit breaker 103 via line 107. The L2 bus bar 106A isconnected to terminal 1 via line 109 and to phase L2 from the maincircuit breaker 103 via line 105. The first two-pole circuit breaker110A may have an example rating of 110 Amperes. The first bus bar 104Aand the second bus bar 106A in the first panel section 102A, may eachhave an example bus bar rating of 225 Amperes.

A second two-pole circuit breaker 110B in the second panel section 102Bmay be oriented as a back feed breaker to connect the L1 bus bar 104B toterminal 3 of the terminal block 142 via line 115. The L2 bus bar 106Bis connected to terminal 2 via line 113. The second two-pole circuitbreaker 110B may have an example rating of 110 Amperes. The first busbar 104B and the second bus bar 106B in the second panel section 102B,may each have an example bus bar rating of 225 Amperes. The NationalElectrical Code allows an extra 20% of electrical power to be added to aconventional 225 Ampere rated panel resulting in a total of 270 Amperes.Since the second circuit breaker 110B protecting this second panelsection 102B is only 110 Amperes, a total of up to 160 Amperes ofphotovoltaic power may be connected to this second panel section 102Bbefore reaching the maximum allowed.

The same calculations may be applied to the first panel section 102A, ifit is desired to add more solar capacity, but that additional solarproduction would not be active when in backup mode.

A relay 118 in the microgrid interconnection device 116, is configuredto be closed and conduct utility power from the main breaker 103 to thesecond two-pole circuit breaker 110B in the second panel section 102Bwhen there is no utility power outage and to be open when there is autility power outage.

When there is no outage, the closed relay 118 in the microgridinterconnection device 116 conducts the phase L1 power from the mainbreaker via line 107, terminal 4, lines 114A, 114B, terminal 3, and line115 to the second two-pole breaker 110B in the second panel section 102Band the L1 bus bar 104B in the second panel section 102B. When there isno outage, the closed relay 118 in the microgrid interconnection device116 conducts the phase L2 power from the main breaker via line 105,terminal 1, lines 112A, 112B, terminal 2, and line 113 to the secondtwo-pole breaker 110B in the second panel section 102B and the L2 busbar 106B in the second panel section 102B. The second panel 102B maythus be connected through the relay 118 to the main breaker 103, inparallel with the first panel 102A when there is no utility poweroutage.

The second panel section 102B of the split-bus electrical panel 100services a back-up system that includes renewable energy power sourcessuch as at least one of a photovoltaic (PV) system or a wind energysystem. The photovoltaic (PV) system with a battery back-up, includes aphotovoltaic solar array 132, a solar inverter 134, and a back-upbattery 120. The back-up battery 120 includes a rechargeable battery, aninverter, a charger, and an outage detector 121. In normal operationwhen there is no outage of power from the utility, the photovoltaicsystem with battery back-up supplements the utility power.

The solar inverter 134 receives direct current from the photovoltaicsolar array 132 and outputs alternating current over lines 136 and 138to a third two-pole circuit breaker 130 in the second panel section 102Bthat may be oriented as a back feed breaker to connect the L1 bus bar104B and the L2 bus bar 106B to the solar inverter 134. The thirdtwo-pole circuit breaker 130 may have an example rating of 60 Amperes.The solar inverter 134 outputs the AC power to the L1 bus bar 104B andthe L2 bus bar 106B in the second panel section 102B via the thirdtwo-pole circuit breaker 130.

The back-up battery 120 includes an inverter that converts directcurrent from the rechargeable battery and outputs alternating current toa fourth two-pole circuit breaker 124 in the second panel section 102Bthat may be oriented as a back feed breaker to connect the L1 bus bar104B and the L2 bus bar 106B to the inverter of the back-up battery 120.The fourth two-pole circuit breaker 124 may have an example rating of 30Amperes. The inverter of the back-up battery 120 outputs the AC powerover lines 126 and 128 to the fourth two-pole breaker 124 and the L1 busbar 104B and the L2 bus bar 106B in the second panel section 102B, tosupplement any insufficiency in photovoltaic power from the solarinverter 134, if needed. In addition, the back-up battery 120 includes arechargeable battery and a charger that receives the utility power (orsolar power) from the fourth circuit breaker 124 to charge therechargeable battery when there is no utility power outage.

The backup battery 120 includes an outage detector 121 that may beconnected to either the L1 phase or the L2 phase outputs 105 and 107from the main circuit breaker 103. The outage detector 121 detects whenthe voltage changes in either or both of L1 phase and L2 phase outputs105 and 107, indicating an outage of utility power. In response, theoutage detector 121 of the back-up battery 120 sends an outage signal122 to the relay 118 in the microgrid interconnection device 116,causing the relay 118 to open during the outage. When the relay 118opens, the second panel section 102B may become isolated from the mainbreaker 103, so that the second panel 102B may be powered only from thesolar inverter 134 and the back-up battery 120.

Branch circuit breakers may, for example, be plugged into either thefirst L1 bus bar 104A or the second L2 bus bar 104B of the first panelsection 102A of the split-bus electrical panel 100, to supply power tovarious non-critical standard loads 108A of the residence. The firstpanel section 102A of the split-bus electrical panel 100 has aninterleaved type of bus connector arrangement with two columns of branchcircuit breakers. Each branch circuit breaker originates on the oppositephase (L1 or L2) from the one above or below it. The 120 VAC branchcircuit loads are connected between a breaker on phase L1 bus bar 104Aand Neutral N or between a breaker on Phase L2 bus bar 106A and NeutralN. The 240 V branch circuit loads may be connected using a firstsingle-pole breaker on Phase L1 bus bar 104A and a second single-polebreaker Phase L2 bus bar 106A. The branch circuit breakers may haveexample ratings in a range of 15 to 90 Amperes.

In this manner, power may be supplied to the critical loads 108Bconnected to the second panel 102B, which must continue to be poweredduring a utility power outage.

When the utility power outage ends and utility power resumes, the outagedetector 121 in the back-up battery 120 detects that the voltage hasreturned to one or both of the L1 phase and L2 phase outputs 105 and 107of the main breaker 103, indicating that the outage of utility power hasended. In response, the outage detector 121 of the back-up battery 120sends a signal that the outage has ended, to the relay 118 in themicrogrid interconnection device 116, causing the relay 118 to close.When the relay 118 closes, the second panel section 102B may bereconnected to main breaker 103, so that it may be powered by theutility power, as well as being powered by the supplementary power fromthe solar inverter 134 and the back-up battery 120.

FIG. 2 is circuit and functional block diagram of an alternate exampleembodiment of the single split-bus electrical panel 100 of FIG. 1,wherein the back-up battery 120′ provides back-up direct current overline 128′ to the solar inverter 134, which is combined with thephotoelectric direct current from the photovoltaic solar array 132. Thecombined currents are converted by the solar inverter 134 to alternatingcurrent that is provided over lines 136 and 138 to the third circuitbreaker 130. FIG. 2 also illustrates an alternate example wherein theoutage detector 121′ is associated with the microgrid connection device116. The outage detector 121′ is configured to detect whether there is autility power outage and to cause the relay 118 to open when a utilitypower outage is detected. Battery power is available over line 122 tooperate the relay 118 during a utility power outage.

The resulting apparatus, system, and method provide a single split-buselectrical panel with back-feed circuit breakers arranged and sized sothat, for example, a single 225 A rated split-bus electrical panel witha 200 A main breaker may be used to connect a far higher photovoltaicpower source than allowed with conventional configurations. Two panelsections of the single split bus electrical are connected in parallel,allowing much more photovoltaic power to be connected. For example, two225 Ampere panel sections of the split-bus panel each have a 110 Ampererated breaker. The panel section's rating may be increased by 120% ofthe 225 Amperes to 270 Amperes. The difference of the 270 Ampere ratingfor the panel section from the 110 Ampere rating for the breaker, allowsa maximum rating of 160 Amperes for photovoltaic power that may beconnected to the panel section.

In the preceding, reference is made to various embodiments. However, thescope of the present disclosure is not limited to the specific describedembodiments. Instead, any combination of the described features andelements, whether related to different embodiments or not, iscontemplated to implement and practice contemplated embodiments.Furthermore, although embodiments may achieve advantages over otherpossible solutions or over the prior art, whether or not a particularadvantage is achieved by a given embodiment is not limiting of the scopeof the present disclosure. Thus, the preceding aspects, features,embodiments and advantages are merely illustrative and are notconsidered elements or limitations of the appended claims except whereexplicitly recited in a claim(s).

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other implementation examplesare apparent upon reading and understanding the above description.Although the disclosure describes specific examples, it is recognizedthat the systems and methods of the disclosure are not limited to theexamples described herein but may be practiced with modifications withinthe scope of the appended claims. Accordingly, the specification anddrawings are to be regarded in an illustrative sense rather than arestrictive sense. The scope of the disclosure should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. An apparatus for maximizing power of aphotovoltaic system to power critical residential loads during a utilitypower outage, comprising: a single, split-bus electrical panel includinga first panel section of the split-bus electrical panel configured tosupply power to non-critical standard electrical loads and a secondpanel section of the split-bus electrical panel configured to supplypower to critical electrical loads by a back-up system, the criticalloads required to be powered during a utility power outage; a firstcircuit breaker in the first panel section connected to a first bus barand a second bus bar of the first panel section, the first circuitbreaker configured to conduct utility power from a utility power source;a second circuit breaker in the second panel section connected to afirst bus bar and a second bus bar of the second panel section, thesecond circuit breaker connected through a relay to the utility powersource in parallel with the first circuit breaker, the second circuitbreaker configured to conduct the utility power from the relay to thefirst bus bar and the second bus bar of the second panel section whenthere is no utility power outage, and to be isolated by the relay fromthe utility power source when there is a utility power outage; a thirdcircuit breaker in the second panel section connected to the first busbar and the second bus bar of the second panel section, and connected toa renewable energy power source of the back-up system, configured toconduct renewable energy power to the first bus bar and the second busbar of the second panel section; and a fourth circuit breaker in thesecond panel section connected to the first bus bar and the second busbar of the second panel section, and connected to a back-up power sourceof the back-up system, configured to conduct back-up power to the firstbus bar and the second bus bar of the second panel section to supplementthe renewable energy power at least when a utility power outage isdetected by the back-up power source.
 2. The apparatus of claim 1,wherein the relay is configured to be closed and conduct utility powerfrom the utility power source to the second circuit breaker when thereis no utility power outage and to be open when there is a utility poweroutage;
 3. The apparatus of claim 2, wherein an outage detector isassociated with the back-up power source and is configured to detectwhether there is a utility power outage and to send an outage signal tothe relay to open when a utility power outage is detected.
 4. Theapparatus of claim 1, wherein the renewable energy power source of theback-up system is at least one of a photovoltaic solar array or a windenergy array.
 5. The apparatus of claim 1, wherein the first, second,third, and fourth circuit breakers are two-pole circuit breakersoperating as back-feed circuit breakers.
 6. The apparatus of claim 1,wherein the utility power is 120/240 VAC Split Phase Electrical power.7. The apparatus of claim 1, wherein the relay is a component of amicrogrid interconnection device.
 8. The apparatus of claim 1, whereinthe second panel is connected through the relay to the utility powersource in parallel with the first panel when there is no utility poweroutage.
 9. The apparatus of claim 1, wherein the back-up power source ofthe back-up system includes a rechargeable battery, a charger, aninverter, and an outage detector that is configured to detect when thereis a utility power outage and send an outage signal to the relay. 10.The apparatus of claim 1, wherein the back-up power source of theback-up system includes a rechargeable battery and a charger thatreceives the utility power from the fourth circuit breaker to charge therechargeable battery when there is no utility power outage.
 11. Theapparatus of claim 2, wherein an outage detector is associated with amicrogrid connection device and is configured to detect whether there isa utility power outage and to cause the relay to open when a utilitypower outage is detected.
 12. An apparatus for maximizing power of aphotovoltaic system to power critical residential loads during a utilitypower outage, comprising: a single, split-bus electrical panel includinga first panel section of the split-bus electrical panel configured tosupply power to non-critical standard electrical loads and a secondpanel section of the split-bus electrical panel configured to supplypower to critical electrical loads by a back-up system, the criticalloads required to be powered during a utility power outage; a firstcircuit breaker in the first panel section connected to a first bus barand a second bus bar of the first panel section, the first circuitbreaker configured to conduct utility power from a utility power source;a second circuit breaker in the second panel section connected to afirst bus bar and a second bus bar of the second panel section, thesecond circuit breaker connected through a relay to the utility powersource in parallel with the first circuit breaker, the second circuitbreaker configured to conduct the utility power from the relay to thefirst bus bar and the second bus bar of the second panel section whenthere is no utility power outage, and to be isolated by the relay fromthe utility power source when there is a utility power outage; a thirdcircuit breaker in the second panel section connected to the first busbar and the second bus bar of the second panel section, and connected toa renewable energy power source and a back-up power source of theback-up system, configured to conduct renewable energy power and back-uppower to the first bus bar and the second bus bar of the second panelsection, the back-up power to supplement the renewable energy power atleast when a utility power outage is detected.
 13. A system formaximizing power of a photovoltaic system to power critical residentialloads during a utility power outage, comprising: a single, split-buselectrical panel including a first panel section of the split-buselectrical panel configured to supply power to non-critical standardelectrical loads and a second panel section of the split-bus electricalpanel configured to supply power to critical electrical loads by aback-up system, the critical loads required to be powered during autility power outage; a first circuit breaker in the first panel sectionconnected to a first bus bar and a second bus bar of the first panelsection, the first circuit breaker configured to conduct utility powerfrom a utility power source; a relay connected to the utility powersource, configured to be closed and conduct utility power from theutility power source when there is no utility power outage and to beopen when there is a utility power outage; a second circuit breaker inthe second panel section connected to a first bus bar and a second busbar of the second panel section, the second circuit breaker connectedthrough the relay to the utility power source in parallel with the firstcircuit breaker, the second circuit breaker configured to conduct theutility power from the relay to the first bus bar and the second bus barof the second panel section when there is no utility power outage, andto be isolated by the relay from the utility power source when there isa utility power outage; a third circuit breaker in the second panelsection connected to the first bus bar and the second bus bar of thesecond panel section, and connected to a renewable energy power sourceof the back-up system, configured to conduct renewable energy power tothe first bus bar and the second bus bar of the second panel section; afourth circuit breaker in the second panel section connected to thefirst bus bar and the second bus bar of the second panel section, andconnected to a back-up power source of the back-up system, configured toconduct back-up power to the first bus bar and the second bus bar of thesecond panel section to supplement the renewable energy power at leastwhen a utility power outage is detected by the back-up power source; andan outage detector associated with the back-up power source, configuredto detect whether there is a utility power outage and to send an outagesignal to the relay to open when a utility power outage is detected. 14.The system of claim 13, wherein the renewable energy power source of theback-up system is at least one of a photovoltaic solar array or a windenergy array.
 15. The system of claim 13, wherein the first, second,third, and fourth circuit breakers are two-pole circuit breakersoperating as back-feed circuit breakers.
 16. The system of claim 13,wherein the relay is a component of a microgrid interconnection device.17. The system of claim 13, wherein the second panel is connectedthrough the relay to the utility power source in parallel with the firstpanel when there is no utility power outage.
 18. The system of claim 13,wherein the back-up power source of the back-up system includes arechargeable battery, a charger, an inverter, and the outage detector.